However, the presumptive Republican nominee for president offered few hints on what he would do differently from the Obama administration. Though a senior adviser, Dan Senor, earlier suggested that Mr. Romney would "respect" an Israeli decision to launch a lone attack, Romney in his speech reiterated the more vague formulation of the Obama administration that "we recognize Israel’s right to defend itself."

He did reproach the president indirectly for chastising the Israeli leaders for saber rattling, a remark made when Mr. Netanyahu last visited Washington.

"It is sometimes said that those who are the most committed to stopping the Iranian regime from securing nuclear weapons are reckless and provocative and inviting war," Romney said. "The opposite is true. We are the true peacemakers."

Romney's visit has escalated the competition between the two campaigns to demonstrate who's a stronger supporter of the Jewish state. Mr. Obama on Friday announced $70 million in additional military aid to help develop a rocket system to intercept missiles from Gaza and Lebanon.

Israeli officials and analysts are anxious about Israel being in the election's spotlight, and would prefer the country to be more of an afterthought. That’s because an election debate over Israel could damage long-term ties between the countries by risking the Jewish state's long cultivated bipartisan support in Washington.

"We don’t want to be part of the issue," says an Israeli diplomat, who was not authorized to speak. "We have very strong bipartisan support and we want to keep it that way. We want there to be strong relations with the US. Not with blue or red."

Romney: Jerusalem is capital

Speaking against the backdrop of Jerusalem's Old City, Romney called the disputed city Israel's capital. That's likely to bother Palestinians and Arab countries who claim East Jerusalem – the portions captured in the 1967 Arab-Israeli War – as the capital of a Palestinian state.

In another dig at Obama – who has been bragging about stepped-up military cooperation with Israel – Romney blamed the president for allowing public disputes to emerge: "Standing by Israel does not mean with military and intelligence cooperation alone," he said. "We cannot stand silent as those who seek to undermine Israel voice their criticisms. And we certainly should not join in that criticism. Diplomatic distance in public between our nations emboldens Israel's adversaries.''

Romney’s portrayal of Iran seemed to echo Netanyahu's apocalyptic comparisons of Iran and Nazi Germany. The Republican nominee said Iran's leaders are "testing our moral defenses" and added "we have seen the horrors of history. We will not stand by. We will not watch them play out again."

His warning that "when the world’s most despotic regimes secure the world’s most dangerous weapons" will lead to war also seemed to echo remarks made by Netanyahu just last week about the need to stop Iran.

Second billing in Romney’s speech was given to the tumult in Syria and the political transition in Egypt. He gave no policy direction on Syria, and urged Egypt to uphold its peace treaty with Israel, as the administration has done.

Absent from the speech was any mention of the peace process with the Palestinians, which has been mothballed for years and shows no signs of resuming. Just two weeks ago, Secretary of State Hillary Rodham Clinton repeated Obama, saying that "the status quo is unacceptable."

Romney's broader critique

This is the second presidential election in which the Jewish state has become a campaign stop. In 2008, both Obama and Sen. John McCain took breaks from campaigning in the US to visit here.

But the open bickering between Obama and Netanyahu over the peace process with the Palestinians and how to confront Iran has made support for Israel an issue for debate, and part of Romney’s broader foreign-policy critique that the administration has failed to stand behind allies and projected weakness.

Romney’s visit is also seen as an attempt to indirectly highlight the fact that Obama did not visit Israel in his first four years of office when he visited other American allies in the Muslim world, stirring up criticism from some Israelis.

"Romney feels that the president may be somewhat vulnerable. Romney may sense that there is some Israeli dismay at some Obama policies and sees an opportunity," said David Horvitz, editor of the Times of Israel news website. "Unfortunately, Israel has become an issue of greater partisan debate than it used to…. That’s tremendously to Israel’s detriment."

Despite Romney’s oft-quoted allegation that Obama has thrown Israel "under the bus," many Israelis are unfamiliar with Romney because they aren’t paying attention to the US election. A recent poll among Israeli Jews by the Begin Sadat Center for Strategic Studies, an institute at Bar Ilan University, showed Romney with a seven percentage point edge over Obama regarding who would better promote Israel’s interests, but 49 percent said they don’t know.

Jewish-American voters at stake

At stake is an attempt by Romney to make inroads with the Jewish American community who have solidly supported Democratic presidential candidates. In 2008, Obama was favored by 74 percent of American Jews, second only to African-Americans among demographic groups, but now that support is at only 68 percent, according to a recent Gallup survey. Some believe that only a slight shift could help capture a crucial swing state like Florida, where Jews make up a significant chunk of the registered voters.

Some have accused Netanyahu, who is known to be on better terms with Republican politicians than Democrats, of feeding into the polarization. Standing alongside Romney on Sunday, the Israeli prime minister took a dig at the administration by saying the administration’s policy of sanctions and diplomacy to pressure Iran had failed to delay Iran's drive for nuclear weapons.

"We have to be honest and say that all the sanctions and diplomacy so far have not set back the Iranian program by one iota," he said.

Just two weeks ago Secretary Clinton said in Jerusalem that sanctions and diplomacy had brought unprecedented pressure on Tehran and needed more time to work.

Bilateral polarization

Some see the increased partisanship as a natural expression of the affinity between the two countries’ respective ideological rivals: The Republicans are more drawn to Netanyahu’s conservative Likud party, and Democrats find common cause with social democrats on the Israeli left, like the Labor Party. A scheduled visit between Romney and the Israeli Labor Party leader was canceled.

Republicans and the Israeli right see common cause "on three issues: the land of Israel, religion, and family values," says Mitchell Barak, an Israeli pollster. "There’s a natural connection to the Israeli left to the Democrats, and vice versa: That’s based on share values of democracy, freedom of religion, freedom of speech, and protection of minorities."

But that risks upsetting a key strategy by pro-Israel allies in the US of cultivating support among both Democrats and Republicans in order to ensure that there’s continuity of US support for Israel regardless of who controls the White House or the Congress.

"It was very easy to stay out of this when American presidential candidates didn’t come to Israel three or four months before the election," says one Jewish American official active in boosting bilateral ties. "If it looks like you are backing one and the other gets elected, you are in trouble."